Background and Purpose: The modified functional reach test (MFRT) is the objective measure for dynamic sitting balance. It quantifies sitting balance in two directions: Forward and lateral reach. So, the purpose of the study was to 1) provide clinical reference value and 2) examine the factors that may influence the anthropometrics measures. Materials and Methods: A total of 200 apparently healthy subjects participated in this descriptive study. All subjects were divided in two groups: Younger (20-39 yr) and middle-aged (40-59 yr). After anthropometric measurement, all subjects performed test by reaching forward and lateral with a closed fist while sitting. MFRT was taken with 3 trials with 15 sec break in between. Results: The mean score of the forward and lateral reach of right and left in group 1 was higher compared to group 2. The normative value of forward reach in group 1 was 34.05 ± 9.03 cm; for lateral reach right and left, it was 18.2 ± 5.26 cm and 17.32 ± 5.21 cm, respectively. For group 2, normative values for forward reach, lateral right and left were 25.18 ± 5.71 cm, 14.02 ± 3.98 cm and 13.53 ± 4.25 cm, respectively. There was no significant correlation of forward and lateral reach measures with the anthropometric characteristics in both the groups, except trunk length and BMI in group 1, which was significantly correlated ( P < 0.001). Conclusion: This study provides clinical reference value for younger and middle age group subjects while anthropometrics do not affect performance except trunk length and BMI in younger age group.

Falls are a part of the downward spiral that can lead to functional limitations, disability, institutionalization, and death. The prevention of falls has become a major focus of public health programs. One component of prevention is the early detection of individuals who are at risk of falling. [1] To develop effective interventions to prevent falls, there must be reliable and valid measures of static and dynamic balance. [2]

Balance is the ability to maintain one's postural control, which limits the body's sway and keeps its center of gravity within its BOS. This control allows an individual to maintain balance when body movement occur. [3] Balance and upright postural control are fundamental components of movement, and this involves the ability to recover from instability and the ability to anticipate and move in ways to avoid instability. [4] Balance has been studied in various ways, by recording biomechanical descriptions of balance reactions by examining physiological components of balance and by investigating changes in the ability of a person to balance across the life span. [5] Numerous researchers have developed objective standing balance measures [6],[7] to test the effectiveness of various interventions. [2] Most studies of balance have been performed with subjects in the standing position. There are various objective standing balance measures, which are appropriate for adults who can stand. [2]

Sitting balance is not a functional activity, but the ability to maintain or attain sitting balance is believed to be necessary to perform functional activities such as dressing, transferring, and eating in seated position. [8],[9],[10] Sitting balance is a pre-requisite for most functional activities, such as dressing, transferring, and eating in a seated position. [11] Lynch et al. defined sitting balance as the ability to maintain control over upright posture during forward reach without stabilization. [5] Biomechanically, specific trunk movements have to occur to maintain postural control in sitting. [3],[12] The ability to balance while reaching for a variety of objects both within and beyond arm's length is critical to independent living. [13] However, frail individuals who are unable to stand unsupported cannot perform the tests. The researchers have neglected the development and study of objective measurements of sitting balance. Only a few tests exist for clinical balance assessment of non-standing individuals. [5]

Functional reach test (FRT) is a quick and simple, single task dynamic test, which was developed by Duncan et al. in 1990 to measure a person margin of stability as well as to maintain balance during functional task. FRT is defined as the maximal distance one can reach forward beyond arm length while maintaining a fixed base of support in standing. [2] It is portable, inexpensive, reliable, precise, and less time-consuming for detecting dynamic balance. [11] The FRT is a balance control; therefore, environmental task and biomechanics constraints must be considered change in the task performance such as trunk rotation or protraction of shoulder blades during reaching. In addition FRT may be affected by variables such as testing procedure and characteristic of subject. [14]

To improve sitting balance and prevent falls from sitting, researchers develop the objective ways to measure dynamic sitting balance. One of such method is the Modified Functional Reach Test (MFRT), which was developed by Lynch and associates in 1998 to assess sitting balance in individuals with spinal cord injury. [5] MFRT examined movement in two directions, forward reach and lateral reach while sitting. Lateral sitting reach is likely to be different from forward reach in that the base of support is different. Other factors such as age [15],[16] and anthropometrics may influence the limits of stability in sitting when reaching forward or laterally. [2] Dean et al. stated that forward reach distance in sitting was positively associated with the magnitude of the trunk and upper arm segmental motion, as well as the active contribution of the lower limbs in healthy persons. Reaching forward in sitting is a challenge to a person's postural control and is suggested to be an indicator of sitting balance. [17]

MFRT is useful for detecting balance impairment, change in balance performance over time, and in the design of modified environments for impaired individual. To use it as an outcome measure, we must have clinical reference value. Unfortunately, there are few literature available for use of MFRT in adult. There is a need of research for the normative values of MFRT in young- and middle-aged group normal subjects. So, the primary purpose of this study was to provide clinical reference value for normal healthy adults in young and middle age group. The second purpose was to determine anthropometric factors, which can influence sitting forward or lateral reach.

Materials and Methods

A sample of convenience was employed. We recruited 206 apparently healthy community dwelling adults between the ages of 20 and 59 volunteered from Sikkim, India. The community dwelling adults were recruited via notice in university notice board, flyers around the local area, other local colleges, and contact with local centers. This was a descriptive study approved by institutional ethical board. The participants were screened based on inclusion criteria; 20-59 year old healthy subjects, both gender, body mass index (BMI): Recommended: For young age group: 18-24 kg/m 2 and for middle age group: 19-26 kg/m 2 . [18] The participants were excluded based on following criteria: Any recent medical condition e.g. musculoskeletal or neurological disorder, visual defect, or any postural pathology. Six individual were excluded because they did not meet the inclusion criteria. The remaining 200 participants were included in the study, which were divided in two aged group; young age (20-39 year); group 1 and middle age (40-59 year); group 2. An inform consent was taken from all participants before data collection.

Prior to study, demographic and anthropometric information regarding gender, age, trunk flexibility, height, weight, BMI, arm length, and trunk length were taken by the investigator. Height was measured in centimeters by standiometer. Weight was measured in kilogram (Kg) by a standard calibrated scale. Arm length and trunk length were measured in centimeters with an inch tape. Arm length was measured from the acromion process to the ulnar styloid process with the arm supported in 90° of abduction. Trunk length was measured from the C 7 spinous process to the seat of the chair. BMI was calculated by using formula: wt/ht 2 (kg/m 2 ). Trunk flexibility was examined by using sit and reach test.

MFRT was performed with the leveled yard stick, which was mounted on the wall at the height of the acromion level in the arm of each participant while sitting unsupported. Hip, knee, and ankle positioned at 90 degree with the feet flat on the floor. Instruction was given for leaning as far as possible with a closed fist in each direction without rotation and without touching the wall. The initial reach was measured with the individual sitting against the back of the chair with the upper-extremity flexed to 90 degree; measurement was taken from the distal end of the third metacarpal along the yardstick. It consists of three conditions over three trials: 1) Sitting with the arm to be measured near the wall and leaning forward, 2) Sitting with the back to the wall and leaning right, 3) Sitting with the back to the wall leaning left and distance was recorded in centimeters. The initial reading was subtracted from the final reading to obtain the final reach tests score. First trial in each direction was a practice trial and was not included in the final result. Overall three trials were recorded for each participant with 15 second rest period in between. Final score for lateral and forward reach was documented in a log book by the investigator.

Data analysis

Data analysis was performed using SPSS Windows; version 16. Level of significance was considered at P < 0.05. Descriptive statistics was calculated as mean, standard deviation, and percentage for all demographic and anthropometric measurement. Also, mean and standard deviation were calculated for lateral and forward reach in both groups. Regression analysis was performed to determine the contribution of anthropometric characteristics to forward or lateral reach.

Results

The mean age of group 1 was 29.20 ± 6 and for group 2, it was 49.19 ± 5.87. The percentage of male and female was 43% and 57% in group 1 and in group 2, it was 53% and 47%, respectively. The recommended BMI for particular age group was appropriate with the mean of 22.91 kg/m 2 for group 1 and 25 kg/m 2 for group 2. All participants were similar in terms of anthropometric characteristics such as trunk flexibility, BMI, arm and trunk length as shown in [Table 1].

[Table 2] revealed mean, SD, and range for forward and lateral reach in both group, and there was significant difference in scores between the forward and lateral reach in each group. But, lateral reach left and right values show similarity in each group. Overall, the mean score of the forward and lateral reach of right and left in group 1 was higher compared to group 2. So, the normative value of forward reach in group 1 was 34.05 ± 9.03 cm, for lateral reach right and left it were 18.2 ± 5.26 cm and 17.32 ± 5.21 cm, respectively. For group 2, normative values for forward reach, lateral right and left were 25.18 ± 5.71 cm, 14.02 ± 3.98 cm and 13.53 ± 4.25 cm, respectively.

The correlation of the MFRT measures with the anthropometric characteristics in group 1, a significant correlation of the body mass index was obtained with all the measure of forward and lateral reach right and left (P < 0.001). The trunk length was also significantly correlated with forward and lateral reach measures. However, other anthropometric characteristics did not show any significant correlation with the measures as given in [Table 3]. In group 2, there was no significant correlation of forward and lateral reach measures with the anthropometric characteristics (P > 0.001) as shown in [Table 4].

Table 3: Correlation of FR, LR(R), LR(L) with anthropometric measures in young age group

Sitting balance is important for functional independence, especially for people who cannot stand. Functional reach described by Duncan and associates [2] is to assess dynamic sitting balance by reaching activity that simulates volitional real-world functional movement like the reaching from a seated position. In the present study, measures of dynamic sitting balance are done on normal healthy individuals, which were divided into two groups, young age group (20-39 years) and middle age group (40-59 years). The measurement of the sitting balance was done in three directions; forward, lateral reach right, and lateral reach left. However, research on objective measures of this type of movement has been limited.

The reference values for MFRT have not been established in previous literature; so, our study reported the score of forward reach, which was 38.05 ± 9.03 cm, lateral reach right 18.20 ± 5.26 cm, and lateral reach left 17.32 ± 5.21 cm in group 1. In group 2, the value for forward reach was 25.18 ± 5.71 cm, lateral reach right was 14.02 ± 3.98 cm, and lateral reach left was 13.53 ± 4.25 cm [Table 2]. Our findings were supported by Mary Thompson et al.[19] who investigated forward as well as lateral reach in normal population of two similar age groups. They reported the score of forward reach, which was 44.9 ± 6.9 cm and lateral reach 29.5 ± 6.1 cm in 20-39 years age group. In another age group of 40-59 years, the forward reach score was 42.1 ± 7.0 cm and lateral reach score was 26.3 ± 5.1 cm. In comparison to Mary Thompson et al.,[19] our study shows mean forward reach distances 38.05 cm and 25.18 cm, respectively, for young- and middle-aged adults, whereas it was 45.4 cm and 44.3 cm, respectively, in their study.

Another study is done by Lynch et al.[5] who investigated forward reach in subjects following a spinal cord injury. They did not report a mean forward sitting reach, but forward excursion ranged from 2.5 cm to 29.1 cm. They also reported a difference between spinal cord injury subjects and healthy adults in sitting forward reach distance. Mary Thompson et al.[19] stated that sitting forward and lateral reach is reliably measure with yardstick in healthy adults, which is in accordance with our study. A review of literature [20] has shown the reference value for FRT in standing position, which was 22 cm for forward reach and 12 cm for lateral reach. Mary Thompson et al.[19] also quoted that reference values for sitting forward reach and lateral reach were 32 and 18 cm, respectively. Our result shows reference values as 38 and 18 cm for sitting forward and lateral reach, respectively.

The anthropometric characteristics of our study did not show any significant correlation with the forward and lateral reach, except for BMI and trunk length, which was significantly correlated with forward and lateral reach (P < 001) in only group 1. Thus, it signifies that BMI and trunk length does influence the reach measures. These findings are consistent with the expectation by Duncan and associates [2] where anthropometric did not affect standing forward and lateral reach score. And, also by Mary Thompson et al.[19] where anthropometric did not affect sitting forward and lateral reach score. It may be because of shorter lever arm in sitting position, and larger base of support could be the cause of greater limits of stability compare to standing.

A study by Kathleen G. Volkman et al.[14] showed that the effect of subjects characteristics on functional reach test have found that there are significant interaction between subject characteristics (such as age, height, and BOS) with the functional reach test method. However, increased height was not correlated with increased FRT scores in adults. Gender has no significant impact on the reach score. These findings are similar with our results. Habib et al.[21] found that height, weight, and base of support were important factors in FRT scores of Pakistani children.

Based on the previous studies, [22],[23] it has been expected that the sitting functional reach excursions to be smaller for the middle age group because age is another factor that can affect balance. The finding was true for both forward and lateral reach. The anthropometric characteristics were similar in both the age group in present study because sitting functional reach excursion was similar for both age groups. Silveira et al.[24] found that there is an influence of gender, age, height, and foot length on the measurement obtained for FR, and only the arm length, body weight, and support base did not interfere. Studies have also found that force platform data may have predictive value for subsequent falls, especially various indicators of the lateral control of posture. Force-plate studies using destabilizing forces evoke a compensatory motor response compared with an anticipatory balance strategy evoked during voluntary movement of the COG when the person performs activities of daily living. [25],[26]

A. Kumaresan [11] studied functional reach in standing and sitting in normal, overweight, and obese subjects and found that balance is influenced by varying BMI. Obese individual shows less standing and sitting functional reach values, when compared to the normal and overweight subjects, whereas overweight individual shows less standing and sitting functional reach values when compared to the normal. There was no significant difference between BMI of both the groups in our study; so, it has no effect on reach test measures. Another study by Deforche [27]et al. on normal and overweight boys of age 8-10 years have found that there was differences in balance and postural skills, and overweight boys displayed lower capacity on several static and dynamic balance and postural skills.

Our study has some limitations. The results are obtained from young and middle age group participants, which cannot be generalized for other age group population. It is necessary to evaluate other measurement variations in further study like center of pressure using force plate to measure loading during reaching movement, spacing of the feet and fear of fall, and also further examination of psychometric properties of MFRT can be explored in different population with large sample size.

Conclusion

The present study provides the reference values of MFRT for young and middle age group that may be useful for clinical reference. So, it can be used as a quick and easy tool for assessment of sitting balance by forward and lateral reach measures.

Acknowledgment

My sincere thanks to Dean, SMIMS, Gangtok, Sikkim for providing support and guidance throughout the study, and also I would like to thank all my participants as it was not possible to do this endeavor without their cooperation.